Nano resonator 'makes objects super visible'

The team from the University of Wisconsin-Madison believe their advance could have implications for everything from photography to solar power.

In a paper published in Physical Review Letters, Zongfu Yu, an assistant professor of electrical and computer engineering, and his collaborators describe a nanoscale device that drastically surpasses previous technology in its ability to scatter light. They showed how a single nanoresonator can manipulate light to cast a very large reflection.

The nanoresonator’s capacity to absorb and emit light energy is such that it can make itself – and, in applications, other very small things – appear 10,000 times as large as its physical size.

“Making an object look 10,000 times larger than its physical size has lots of implications in technologies related to light,” Yu said in a statement.

The researchers realised the advance through materials innovation and a keen understanding of the physics of light, which can amplify itself as the surrounding environment manipulates the physical properties of its wave energy. The researchers are said to have taken advantage of this by creating an artificial material in which the wavelength of light is much larger than in a vacuum, which allows light waves to resonate more powerfully.

The device condenses light to a size smaller than its wavelength, meaning it can gather a lot of light energy, and then scatters the light over a very large area, harnessing its output for imaging applications that make microscopic particles appear huge.

“The device makes an object super-visible by enlarging its optical appearance with this super-strong scattering effect,” said Ming Zhou, a Ph.D. student in Yu’s group and lead author of the paper.

The very small optical device can receive light energy from all around and yield a surprisingly strong output. In imaging, this presents clear advantages over conventional lenses, whose light-gathering capacity is limited by direction and size.

“We are developing photodetectors based on this technology and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions,” Yu said.

Given the nanoresonator’s capacity to absorb large amounts of light energy, the technology also has potential in applications that harvest the sun’s energy with high efficiency.

“This research opens up a new way to manipulate the flow of light, and could enable new technologies in light sensing and solar energy conversion,” said Yu.